1. Spectroscopy 3: Magnetic Resonance CHAPTER 15

2. Conventional nuclear magnetic resonance Energies of nuclei in magnetic fields Typical NMR spectrometer The chemical shift (effect of nearby nuclei) Fine structure (nuclear spin-spin coupling) Pulsed techniques in FT-NMR

3. The 1 H-NMR low-resolution spectrum of ethanol

4. Fig 15.6 The 1 H-NMR high-res spectrum of ethanol Integrated signal singlet quartet triplet 1 3 2 Fine structure

5. Fine Structure Each magnetic nucleus may contribute to the local field of adjacent nuclei ∴ Resonance frequencies are modified Strength of interaction given by the coupling constant, J (Hz) J is independent of applied mag field, B o

6. Margin pg 526 n equivalent nuclei split adjacent spin(s) into n+1 lines with intensity distribution given by Pascal’s triangle :

7. Fig 15.15 Origin of the 1:2:1 triplet in the proton resonance of a –CH 3 group from coupling with –CH 2 protons e.g., CH 3 CH 2 OH ⇇⇉ ⇆ ⇄ B0B0 ⇉ ⇇ ⇆ ⇄

8. Fig 15.16 Origin of the 1:3:3:1 quartet in the proton resonance of a -CH 2 from coupling with -CH 3 protons e.g., CH 3 CH 2 OHB0B0

9. Spectrum 1Empiricial formula C 4 H 8 O

10. Spectrum 2Empiricial formula C 4 H 8 O 2

11. Spectrum 3Contains C, H, OMW = 72